On-Grid
The most common PV system
The grid-tied, on-grid or grid-interactive solar rooftop system is the most common type of PV system.
In this battery-less system, the solar generation is first used to meet the demand of the existing loads and any excess generation is exported to the grid. If there is a short-supply or no solar generation, then the required energy is imported from the grid. Export & import are calculated with the help of a PV - directional meter
In this type of system, energy usage depends on solar generation, running loads & grid availability.
When solar generation = running loads, excess generation is exported to grid, measured as exported power on the meter
When solar generation < running loads, excess energy needed will be imported from the grid, measured as imported power
hen solar generation = running loads, there is no import or export
When solar generation = zero, could be under two cases,
When the grid is shut, solar stops generating keeping safety factors of maintenance
During the night, where the power is imported from the grid.
A bi-directional net meter records the exported and imported electricity and the consumer is charged only for the net electricity consumed from the grid at the end of the billing cycle.
The above video explains how grid-tied solar system and net metering work:
Off-Grid
Best suited for Remote areas
An off-grid solar system is best suited for remote areas with poor or no access to the grid. As the name suggests, this solution is completely independent of the grid and can be configured to power a wide range of appliances from lights and fans to fridges, washing machines, computers and even air-conditioners!
In this setup, solar panels convert sun rays into direct current (DC) electricity, which is used to charge batteries. An inverter then converts the electricity stored in the batteries into alternating current (AC). The AC electricity can then power the dedicated load. Any excess power generated is stored in the battery bank for use later.
